System and method to monitor audio loudness and provide audio automatic gain control
An audio loudness data collection module collects and stores audio data. The data can be stored for a first time period. A monitoring system can access and store the audio data collected and stored by the loudness data collection module according to a second time period. The stored audio data can be processed and displayed to a user in a number of ways. The data can also be used to provide loudness data control. For example, a loudness data control module can perform an audio AGC function to control audio loudness.
1. A method for audio automatic gain control to control audio loudness in a television broadcast system, comprising:
receiving television programming data that includes audio data from at least one data source, wherein the television programming data includes a plurality of channels;
collecting audio data samples for each channel from the television programming data;
determining an audio loudness for each channel from the audio data samples;
averaging the audio loudness for each channel over a first time period as a sample average;
comparing the sample average to a target loudness for each channel; and
adjusting the collected audio data samples for a channel in accordance with the comparison.
2. The method of claim 1 , further comprising:
averaging the audio loudness for each channel over consecutive time periods to generate a plurality of sample averages;
averaging the plurality of sample averages over a second time period;
comparing the average of the plurality of sample averages to a target loudness; and
adjusting the collected audio data samples for a channel in accordance with the comparison.
3. The method of claim 2 , further comprising:
determining whether a minimum number of sample averages have been determined; and
performing the comparing and adjusting steps only if the minimum number of sample averages have been determined.
4. The method of claim 1 , wherein the automatic gain control is performed by a transport processing system in a head-end of a television broadcast system.
5. The method of claim 4 , wherein the audio loudness for each channel is stored in a memory associated with the transport processing system.
6. The method of claim 1 , wherein the adjusting is performed by updating a scale factor in a header of an MPEG-1, layer II audio data stream for a channel.
7. The method of claim 1 , wherein the adjusting is performed by updating a dialnorm in a header of an AC-3 audio data stream for a channel.
8. The method of claim 1 further comprising establishing an automatic gain control baseline for each channel.
9. The method of claim 8 further comprising adjusting audio loudness for a channel by forcing the automatic gain control baseline to equal a target audio loudness.
10. A system for audio automatic gain control to control audio loudness in a television broadcast system, comprising:
a head end that receives television programming data corresponding to a plurality of channels from one or more data sources and multiplexed the receives television programming data into a television programming stream that includes audio data for each channel;
a transport processing system in the head end that receives the television programming stream and comprises:
a loudness data collector to collect and store audio loudness data for each channel as audio data samples; and
a loudness data control module to perform loudness control on the collected and stored audio loudness data, wherein the loudness data control module:
determines an audio loudness from the audio data samples;
averages the audio loudness over a first time period as a sample average;
compares the sample average to a target loudness; and
adjusts the collected audio data samples in accordance with the comparison.
11. The system of claim 10 , wherein the loudness data control module further:
averages the audio loudness over consecutive time periods to generate a plurality of sample averages;
averages the plurality of sample averages over a second time period;
compares the average of the plurality of sample averages to a target loudness; and
adjusts the collected audio data samples in accordance with the comparison.
12. The system of claim 11 , wherein the loudness data control module further:
determines whether a minimum number of sample averages have been determined; and
performs the comparing and adjusting steps only if the minimum number of sample averages have been determined.
13. The system of claim 9 wherein the transport processing system is located in a head-end of a television broadcast system.
14. The system of claim 13 , wherein the audio loudness is stored in a memory associated with the transport processing system.
15. The system of claim 10 , wherein the loudness data control module updates a scale factor in a header of an MPEG-1, layer II audio data stream to adjust the collected audio data samples.
16. The system of claim 10 , wherein the loudness data control module updates a dialnorm in a header of an AC-3 audio data stream to adjust the collected audio data samples.
17. The system of claim 10 , wherein the loudness data control module establishes an automatic gain control baseline for each channel.
18. The system of claim 17 further comprising adjusting audio loudness for a channel by forcing the automatic gain control baseline to equal a target audio loudness.